N - (p-n-alkoxycarbonyloxybenzylidene)-p&#39;-n-butoxyaniline liquid-crystal compounds

ABSTRACT

THERE IS DISCLOSED THE PREPARATION OF LIQUID-CRYSTAL COMPOUNDS OF THE STRUCTURE:   CXH(2X+1)-O-CO-O-(1,4-PHENYLENE)-CH=N-(1,4-PHENYLENE)-O-   C4H9   WHERE X IS AN INTEGER OF 1 TO 10. THE COMPOUNDS ARE PREPARED BY THE REACTION OF PARA-N-BUTOXYANILINE AND PARA-NALKOXYCARBONYLOXYBENZALDEHYDE.

United States Patent 3,769,314 N (p-n-ALKOXYCARBONYLOXYBENZYLIDENE)-p'-n-BUTOXYANILINE LIQUID-CRYSTAL COM- POUNDS Edward L. Steiger andHeinz J. Dietrich, Toledo, Ohio, assignors to Owens-Illinois, Inc. NoDrawing. Filed July 14, 1971, Ser. No. 162,668 Int. Cl. C07c 119/10;G021 N16 US. Cl. 260-463 3 Claims ABSTRACT OF THE DISCLOSURE There isdisclosed the preparation of liquid-crystal compounds of the structure:

where x is an integer of 1 to 10. The compounds are prepared by thereaction of para-n-butoxyaniline andpara-nalkoxycarbonyloxybenzaldehyde.

This invention relates to the preparation of mesomorphic compounds. Moreparticularly, this invention relates to the preparation of mesomorphiccompounds which may be utilized in display type devices.

Mesomorphic materials, typically referred to as liquidcrystal materials,are organic compounds in a transition state between crystalline solidand normal isotropic liquid forms. Such materials are well known in theprior art. Likewise, it is known in the prior art to use suchliquidcrystal materials in display type devices.

In accordance with this invention, there is preparedN(p-n-alkoxycarbonyloxybenzylidene) p n butoxyaniline liquid-crystalcompounds of the structure:

0 l n-C H2 1+1 0 A: O CH=N O (1411 -11 where x is an integer of 1 to 10,preferably 1 to 5, by the reaction of para-n-butoxyaniline,

and para-n-alkoxycarbonyloxybenzaldehyde,

0 n-oxnhnoiio@ono where x is as defined above.

The para-n-alkoxycarbonyloxybenzaldehydes of this invention are preparedby reacting para-hydroxybenzaldehyde with an appropriate n-alkylchloroformate (which are both commercially available) in the presence ofan inorganic base such as lithium hydroxide, sodium hydroxide, orpotassium hydroxide and water. Organic bases such as pyridine ortrialkyl amines under dry conditions may be substituted. These reactionsare conducted under subambient temperatures, e.g. 0 to C. Thepara-hydroxybenzaldehyde, inorganic base and water or organic base areplaced in a reaction vessel. The n-alkyl chloroformate is then slowlyadded with external cooling to control temperature exotherm. Afteraddition, the mixture is allowed, under agitation, to warm to roomtemperature and remain for 2 to 4 hours. The reaction mixture is thenquenched into water and the product is isolated by extraction with awater immiscible organic solvent, first under basic conditions and thenfollowed by acidic conditions. The product is purified by fractionaldistillation.

The following equation is representative of the reac- 3,769,314 PatentedOct. 30, 1973 tion of para-n-butoxyaniline andpara-n-alkoxycarbonyloxybenzaldehyde:

The para-n-butoxyaniline is commercially available. It may be typicallyused Without further purification.

Schifif bases are prepared by refluxing equimolar quantities of thep-substituted benzaldehyde and aniline in anhydrous ethanol for about 4to 6 hours. The solvent and water are removed and the residuerecrystallized several times from ethanol until the transitiontemperatures remain constant. The crude yields ranged from 70 to Theinfra-red spectra show a strong band at 1629- cm.- corresponding to thecarbon nitrogen double bond in Schiff base compounds. Other absorptionsare compatible with the expected structures.

Transition temperatures are determined on a Leitz Ortholux polarizingmicroscope using a Mettler FP-2 heating stage.

N(p ethoxycarbonyloxybenzylidene) p' n butoxyaniline (where x is 2 inthe basic structure) was prepared in accordance with this invention. Thestructure Was analyzed at 70.57 percent by weight carbon, 6.91 percentby weight hydrogen, and 4.18 percent by weight nitrogen compared withcalculated theoretical analysis values of 70.36 percent by weightcarbon, 6.79 percent by weight hydrogen, and 4.10 percent by weightnitrogen. The compound changed from the crystalline to the nematic phaseat about 98.5 C. and from nematic to isotropic at about 118.7 C.

N(p n butoxycarbonyloxybenzylidene)-p'-butoxyaniline (where x is 4 inthe basic structure) was prepared in accordance with this invention. Thestructure was analyzed at 71.27 percent by weight carbon, 7.41 percentby weight hydrogen, and 3.98 percent by weight nitrogen compared withcalculated theoretical analysis values of 71.52 percent by weightcarbon, 7.37 percent by weight hydrogen, and 3.79 percent by weightnitrogen. The compound changed from the crystalline to the nematic phaseat about 88.7 C. and from nematic to isotropic at about 105.5 C.

The liquid-crystal compounds prepared in accordance with this inventionmay be utilized in display devices, especially of the electronic type.

Such devices typically comprise a thin layer of liquid crystalssandwiched between two sheets of glass. Normally, the thin layer ofliquid-crystal material is clear, but when an electric field is appliedto it, some portions or regions of the material become turbulent so asto scatter light. By controlling the size and shape of the turbulentregions, images can be formed. Primarily, this effect is obtained by useof liquid-crystal materials of the nematic type.

Various embodiments of liquid-crystal electro-optical devices aredisclosed and illustrated in US. Letters Patents 3,401,262 and3,410,999; Proceedings of the IEEE, Vol. 56, No. 12, December 1968,pages 2146 to 2149; The Glass Industry, August 1968, pages 423 to 425,Chemical and Engineering News, Sept. 30, 1968, pages 32 and 33; PhysicsToday, July 1970, pages 30 to 36; Electronics, July 6, 1970, pages 64 to70; US. Letters Patent 3,322,485 to Williams.

It is also contemplated using the liquid-crystal compounds in a chargestorage display/memory device, especially multiple gas dischargedisplay/memory panels which have an electrical memory and which arecapable of producing a visual display or representation of data such asnumerals, letters, television display, radar displays, binary words,etc.

Multiple gas discharge display and/or memory panels of the type withwhich the present invention is especially concerned are characterized byan ionizable gaseous medium, usually a mixture of at least two gases atan appropriate gas pressure, in a thin gas chamber or space between pairof opposed dielectric charge storage members which are backed byconductor (electrode) members, the conductor members backing eachdielectric member being transversely oriented to define a plurality ofdiscrete discharge volumes and constituting a discharge unit. In someprior art panels the discharge units are additionally defined bysurrounding or confining physical structure such as by cells orapertures in perforated glass plates and the like so as to be physicallyisolated relative to other units. In either case, with or without theconfining physical structure, charges (electrons, ions) produced uponionization of the gas of a selected discharge unit, when properalternating operating potentials are applied to selected conductorsthereof, are collected upon the surfaces of the dielectric atspecifically defined locations and constitute an electrical fieldopposing the electrical field which created them so as to terminate thedischarge for the remainder of the half cycle toaid in the initiation ofa discharge on a succeeding opposite half cycle of applied voltage, suchcharges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of any conductivecurrent from the conductor members to the gaseous medium and also serveas collecting surfaces for ionized gaseous medium charges (electrons,ions) during the alternate half cycles of the A.C. operating potentials,such charges collecting first on one elemental or discrete dielectricsurface area and then on an opposing elemental or discrete dielectricsurface area on alternate half cycles to constitute an electricalmemory.

An example of a panel structure containing nonphysically isolated oropen discharge units is disclosed in U.S. Letters Patent 3,499,167issued to Theodore C. Baker et al.

An example of a panel containing physically isolated units is disclosedin the article by D. L. Bitzer and H. G. Slottow entitled The PlasmaDisplay Panel-A Digitally Addressable Display With Inherent Memory,Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco,Calif., November 1966, pages 541-547. Also reference is made to US.Letters Patent 3,559,190.

In the operation of the panel, a continuous volume of ionizable gas isconfined between a pair of dielectric surfaces backed by conductorarrays forming matrix elements. Typically one or more of the dielectriclayers are photoemissive. The cross conductor arrays may be orthogonallyrelated (but any other configuration of conductor arrays may be used) todefine a plurality of opposed pairs of charge storage areas on thesurfaces of the dielectric bounding or confining the gas. Thus, for aconductor matrix having H rows and C columns the number of elementaldischarge volumes Will be the product H x C and the number of elementalor discrete areas will be twice the number of elemental dischargevolumes.

In addition to the matrix configuration, the conductor arrays may beshaped otherwise. Accordingly, while the preferred conductor arrangementis of the crossed grid type as discussed herein, it is likewise apparentthat where an infinite variety of two dimensional display patterns arenot necessary, as where specific standardized visual shapes (e.g.,numerals, letters, words, etc.) are to be formed and image resolution isnot critical, the conductors may be shaped accordingly. ,7

The gas is one which produces light (if visual display is an objective)and a copious supply of charges (ions and electrons) during discharge.In an open cell Baker et al. type panel, the gas pressure and theelectric field are sufiicient to laterally confine charges generated ondischarge within elemental or discrete volumes of gas between opposedpairs of elemental or discrete dielectric areas within the perimeter ofsuch areas, especially in a panel containing non-isolated units.

As described in the Baker et al. patent, the space between thedielectric surfaces occupied by the gas is such as to permit photonsgenerated on discharge in a selected discrete or elemental volume of gasto pass freely through the gas space and strike surface areas ofdielectric remote from the selected discrete volumes, such remote,photon struck dielectric surface areas thereby emitting electrons so asto condition other and more remote elemental volumes for discharges at auniform applied potential.

With respect to the memory function of a given discharge panel, theallowable distance or spacing between the dielectric surfaces depends,inter alia, on the frequency of the alternating current supply, thedistance typically being greater for lower frequencies.

In the practice of this invention, it is contemplated that a particularliquid crystal may be prepared and/or utilized alone or in combinationwith other liquid-crystal compositions of the same or different family,e.g. such as a mixture of 2 or more compositions. This may be especiallydesirable since mixtures of compounds may have lower transitiontemperatures than the individual compounds.

We claim:

1. As a composition of matter, a compound having the chemical structure0 n-onznmii 0 CH=NO oirt-n where x is an integer of 1 to 5, saidcompound exhibiting liquid-crystal properties.

2. The invention of claim 1 wherein x is 2 and the compound changes fromthe crystalline to the nematic phase at about 98.5" C. and from nematicto isotropic at about 118.7 C.

3. The invention of claim 1 wherein x is 4 and the compound changes fromthe crystalline to the nematic phase at about 88.7 C. and from nematicto isotropic at about 105.5 C.

References Cited UNITED STATES PATENTS 3,540,796 11/1970 Goldmacher etal. 350- 3,675,987 7/1972 Rafuse 350160 2,027,902 1/1936 Dahlen 260-566LEWIS GOTIS, Primary Examiner D. G. RIVERS, Assistant Examiner US. Cl.X.R.

252-407; 350l60 LC

